Slack adjusting mechanism



Oct. 1, 1935. H. w. ALDEN :1- AL 2,015,881

SLACK ADJUSTING MECHANISM Filed Dec. 27, 1953 Herber/ MIA/den Laurence1?. Blake/Ida]:

Patented Oct. 1, 1935 V SLACK ADJUSTING MECHANISM i Herbert W. Alden andLaurence B. Buckendale,

' Detroit,Mich., assignors to The-Timken-De troit Axle Company, Detroit,Mich., a corporai tion of Ohio Application December 21, 1933, Serial No.704,132

9 01a .(o1.1as -19s) This invention relates to amechanism wherein twomembers are relatively adjustable for the purpose of taking up play orcompensating for wear. ,.More specifically the present invention isconcerned with slack-adjusting mechanisms for association with operableparts of automotive vehicles, and particularly for associationwithbrakes and the operating means therefor.

. This application, is an improvement, over the l0 mechanism disclosedin an appl cation of Laurence, R. Buckendale, Serial Number 687,687,filed August 3l. 1933101 ,Slack, adjuster.. The operation of thislast-mentioned mechanism is restricted in angular movement foradjustment 1&- purposes, to the length of the threaded portion of anadjusting bolt. "Due to the limited angular movement which can becompensated for by ad Justment, the thickness of the we'aringmaterial(such as brake lining on a brake shoe) is limited 20 by theangularmovement provided in the adjusting means.. It has been found, forexample, that withthe mechanism of said earlier. application, and usingthe ordinary type of actuating cam, the full amount of adjustment cannotbe obtained 25. with linings of more than three-eights of an inch inthickness.

It is, desirable upon occasion to use' thicker brake linings, such as,for example,three-quarters of an inch thickness. Accordingly, it is thepri- 30. mary object of the present invention to provide a slackadjuster of the angularly adjustable type which will becapable ofmanipulation to effect a greater take-up or compensation than hasheretofore been deemed possible; and more specifically, 35 since themechanism of the aforementioned application Serial Number $87,687 hasnumerous advantages and operates satisfactorily within a given angularrange, it is a major object of this invention to increase the adjustmentrange oi 40 that particular mechanism while retaining the improvementsand advantages ofthe latter.

Therefore, with reference to vehicle b'rakes,it ,follows that it is anobject of this invention to provide a brake slack adjusted ofthecharacter 45 above referred to that will provide for suflicientadjustment to'compensate'for complete wear of relatively thick brakelinings.

It is a further object to provide a slack ad-,

justed mechanism that will require only one two- 50 handed adjustmentthroughout the life of the lining, the other necessary adjustments beingaccomplished with one hand. I r 1 It is a further object to provide aslack-adjuster mechanism havingunusually great angular ad- 66 lustingmovement but yetrequiring the least possible room axially on the shafton which it is placed. v i

A preferred embodiment of the improvedmechanism of thisapplication isdisclosed in the accompanying drawing, which is a part of this Iapplication and. wherein: 4 o

Figure 1 is a side elevational view in partial vertical section,

Figure 2 is a section through Figure 1 taken [substantially on theline IIII, i

Figure 3 is a side elevational.viewlof the actuatingplates of theinvention, and

Figure 1 is a view identical withFigurel, except that the mechanism isshown in its position of maximum adjustment, I 18 With continuedreference to the drawing wherein like reference characters indicate likeparts throughout the several figures, and with particular reference toFigure'2, numerals I and 2 indicate the legs of a yoke member generallydesignated 20 by numeral 4, which is adapted to embrace all other partsand freely rotate on a supporting shaft 6. The, yoke 4 has an upperextension 5 for actuating the same; and the shaft 6 is designed to berotated by mechanism later described, when'the extension 5 is pushed orpulled in the proper direction.

The free or outer endof shaft 6 has a reduced portion 8, and spacedtherefrom is a circumferen tial groove l0. A series ofv serrations I2,running parallel to'the axis of theshaf t andof substantially the samedepth as the groove I0, is provided on the shaft between the groove andthe reduced portion. The diameter of groove I0 is the same as thediameter of the reduced portion 8. Fitting, into groove llll, aspermitted by a U- slot l5, isa plate member l6 for positioning thewholemechanism .uponfshaft '5. 'I'I'he shape of this plate member isfully'disclosed in Figure 3.

A second member I6 is fitted on the reduced por- 40 tion 8inparallelisrn with the first Both of these members arefreelyrotatableon shafti 8. Membersli are'provided with apertures 2|;through which is inserted a pin 23. Pin 2 3is adapted to rotate'freelywithin apertures 20 for a purpose which will presently appear, and isprovided witl.

threaded apertures 25 equally spaced from its "ends.""

' ImmediatelyadJacent members it andplaced toward the insides'thereofare washers 21 and 28 which areadapted to fit around pin 23. when thepin 23 is inits assembled relation with members l6 and washers 21 and28are in place, the threaded aperture 25 lies between said members andwashers and is equally Wed therefrom "to tnenee'imay; be mad much ismaller the.

There is slight clearance provided between washers 21 and 28 andthreaded portion 30 of bolt32 so that no binding will occur. s I

Pin 23 is adapted to swivel in apertures 20 in undesirable twistingforces at this point}.

ate washers 21 and 28 by bending members I6 inwardly, said bend to beonly around aperture 20 would coincide with the innermost portions 'ofwashers 21 and 28 as disclosed. However, the illustrated form ispreferred because it requires only one set of stamping dies formakingfbo'th members I6. Identity of thetwoparts l 6 has the f heradvantage'of requiring-stocking of but a" single part. I j

Bolt 32 is furthermore provided witha suitable latching assembly whichretains'the bolt in its adjusted relation. In the present instance thelatch assembly comprises alplurality of rivets 33 whichare secured tobridge'34 in any suitable manner and a washer35 which is preferablypositioned upon a squared portion of bolt 32 and provided withperipheral latching formations adapted to contact rivets 33. Washer 35is held inyielding contact with rivets 33 by means of a suitable coilspring 35' which encircles the squared portion of bolt 32 "and reactsagainst aw'asher 36 which is'mounted on bolt 32 and adapted to rotatetherewith. A snap ring 35' maintains washer 36 against axial movementalong bolt 32. Spring 35' is ofsufiicient strength to prevent bolt 32from jarring 0r shaking loose but is not strong enough to prevent simpleadjustment thereof by the fingers of one hand. For a more detailed dis-'cussion of the latching means 'associated'with the bolt 32 referencemay be had to the above; mentioned copending application whereinthemechanism is described in detail. I p

. Interposedbetween members 16 and complementally'fitting the serratedportion of theshaft .6 is' "an internally serrated collar 31 havinganvarm 38, which at its outer extremity iscentrally apertured, as at 40,to receive a clevis pin 42 which likewise is inserted through apertures44 in members I6. This pin is maintained in position by a cotter pin 6|At approximately ,90 to arm 38 the collar 31 is'slit to form ears 45 and46. The ear 46 has a threaded aperture, and the other ear, 45, has asmooth aperture 49 in'alinement with the threaded aperture 41. Acaps'crew v5|) projects freely through' aperture 49 and'is threadedintothe ear 46 to draw the two ears together, and thereby couple the'shaft 6and the'arm 38 for unitary oscillation. Lock washer, 53 is provided forlocking capscrew 50. in place. I V

It be noted that the clamping bolt50 does not contact the shaft and inno way positions the mechanism axially thereof. Positioning isaecomplished as before mentioned, by thatmember ls hic cooperates with:the g'r'oio ejil or] i va t ons m"t attn itwiwi h of t rated portionislavailable forlftorquetrans'fer Plates. I6. are. providedwith ,althi'rd, anerture er the same size as aperture 44 and pieces betweensaid last-mentioned aperture and aperture 20. Aperture is also spacedradially from the center of plate IS the same as aperture 44, and thusis designed to receive the pin 42 when a major adjustment is made in amanner hereafter de- 5 scribed.

,A bushing :51 is interposed between leg I of yoke- 4 and-thereduced-diameter 8 of shaft 6. Said bushing 51 is press-fitted into theaperture provided therefor in leg I, said aperture being of 10 the samesize as the corresponding aperture in i leg Bushing 51 has a freelyrotating fit on the members I6 in order that bolt 32 will not receiveshaft portion 8.. The insertion of this bushing leg lsor leg 2 makes thedifference between a It may be said here that it is possibleto elimin-prig t hand and left-hand slack adjuster. That 1 is, should-the adjusterbe required for use on a shaft whose outermost end is under leg 2, theso that the innermost portion of said members bushing would then beomitted from leg I and press-fitted into leg 2. Therefore, one, of thedeidentical whether they are to be used for right- 25 hand or left-handslack adjusters Operation With the mechanism in the position shown inFigure l which is the position when the brake lining is new,theadjusting bolt'32 may be rotated by hand or with a. suitable tool ifdesired and the members I6 through the interconnection of bolt 32and'pin23 will be moved in a counter clockwise direction due to the threadedconnection between bolt 32 and pin 23. It will thus be apparent thatav'eryiine adjustment of the angular'rela- ,tion of the members I6 and Imaybe obtained. In View of the fact that the members I 6 are rigidlyconnectedto themember 31 by pin 42 passing througharin 38 of member 31and apertures ,44 or 55 in members I5; the member 31 will assume thesame angular position with respect to member I as-the members I6will'take. The shaft 6 is secured'to member 31 and is, therefore, caused45 to rotate therewith. From a consideration of the above operation itwill be clear that the cam (not shown) carried by shaft 5 and adapted tospread the brake shoes will be forced to assume an angular position withrespect to the cam faces 50 provided on the brake shoes, therebyspreading them apart a definite amount depending upon the angularmovement of" shaft 6. This angular disposition of thebrake operating camis independ- -ent of the rotation incident to movement of member I dueto the vehicle operator's actuation of the brake pedal. It will,therefore, be clear to one familiar with the ordinary brake operatingsame as 'disclosedfinxthe" aforementioned iBuck- "endale application,but in" the 'Buckendale application, that 'is the extent of theadjustment. 'YVithf ;adde'd-' features {a mad or adjustment can now be"made-'tof quickly take up a large 'amountof'slack andposition the partstorrur- 7'5 ure 1). Whenthis hgsbeendone cotter pin 6| f the clevis pinmay be moved so that aperture 40 is brought into alinement withapertures 55 of plates ii, at which time clevis pin 42 is insertedtherethrough and positioned against coming out by replacing cotter pin6|.

The angle between apertures 44 and 55 of plate I6 is substantially equalto the angular movement obtained by threading bolt 32 through pin 23 tothe maximum adjustment position. Therefore, with the arm 38 in its newposition the cam or cam shaft 6 is essentially in the same positionrelative to the brake shoes as it was before pin 23 was threaded back toits original location. This operation just described is the only timethat two-handed adjustment is necessary. Now, the mechanism is ready forrepetition of small periodical one-handed adjustments by means of thehead of adjusting bolt 32, and when such adjustment is completed themechanism will be in the position shown in Figure 4.

It will readily be seen that the described mechanismhas the advantage ofaffording double the adjustment that normally can be obtained withsimilar devices.

The invention may be embodied in other speciflc forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope ':of -the invention being indicated bythe appended claims rather than by the foregoing description, and allchanges which come within thefmeaning and range of equivalency of theclaims are therefore intended to be embraced therein.

What is claimed and desired to be secured by Uni'ted'States LettersPatent is:

1"; a slack adjuster of the angularly adjustable type, comprising ashaft, an operating nientber adapted to freely rotate about said shaft,a'second member mounted for rotation with said shaft, means foroperativelyinterconnecting said members comprising means whereby smallangular adjustments may be made throughout a limited angular range andmeans adapted to alter the angular relation between said means formaking small angular adjustments and said sec- "end member whereby thefull range of angular adjustment permitted by said first-mentionedadjusting means may be again made available for use.

2. A slack adjuster comprising a shaft, a lever secured to said shaftand adapted to rotate therewith, a pair of spaced members carried bysaid shaft at opposite sides of said lever, means for adjustablyinterconnecting said members and i said lever, an operating memberfreely mountequal to the unreduced'xdi- 1 a' lever secured to said ser-"thereby'adaf pted to rotate-iwith 'ofl o'per'able freelyrotatable whichfits upon said P reduced "'--'interconnecting said freely me "said 1lever for unitary angular movement.

4. A slack adjuster comprising a shaft pro- 1 vided with a reduced endportion and an annular groove of a diameter equal to the diameter ofsaid reduced portion, a serrated portion separating said reduced portionfrom said groove and being of a diameter equal to the unreduced 5diameter of said shaft, a lever secured to said serrated portion andthereby adapted to rotate with said shaft, a pair of operable freelyrotatable members one of which is retained in said groove and the otherof which fits upon said re- 20 duced portion, a bifurcated operatingmember having legs apertured to a diameter equal to the unreduceddiameter of said shaft, one of said leg apertures fitting the shaftadjacent said groove and the other loosely surrounding said re- 5 ducedportion, and a bushing adapted to fill the space between said otheraperture and said reduced portion of the shaft, whereby the slackadjuster may be used either as a left hand or right hand unit employingidentical parts.

5. In a wear compensating or slack adjusting mechanism, a shaft, agroove in said shaft, an operating member carried by said shaft, a leversecured to said shaft, a plate provided with a slot adapted to fit saidgroove, adjustable means 35 interconnecting said operating member andsaid plate, means interconnecting said lever and said plate, said plateadapted to be associatedwith said groove by a motion in a plane normalto the axis of said shaft, whereby the plate, after 40 being connectedto said lever and said operating member, prevents axial movement of themechanism along said shaft.

6. In a slack adjuster, a shaft; a groove formed upon said shaft; acontinuously serrated portion on said shaft; a lever comprising anannular collar, said collar being split to form a pair of ears; a boltspaced from said shaft and adapted to be freely received in one of saidears and screwed into the other of said ears whereby the lever issecured to said serrated portion to obtain rotation of said shaft; anoperating member carried by said shaft; and means adapted to fit saidgroove and connected to said lever and said operating member wherebyaxial movement of the assembly is prevented relative to the shaft.

7. In a slack adjuster, a shaft, an operating member freely mounted onsaid shaft, a lever secured to said shaft, a plate provided with aplurality of angularly spaced apertures and freely mounted on saidshaft, means interconnecting said plate and said operating member, andmeans designed for cooperation with any one of said apertures for:-interconnecting said plate and said lever whereby selective angularpositioning of said plate and said operating member and said plate andsaid lever respectively may be obtained.

8. In a slack adjusting mechanism, a shaft, a member fixed to saidshaft, a second member rotatably carried by said shaft, multiplecoupling means between said members to vary the angular relationshiptherebetween, said multiple coupling means including means for making0011- 7 tinuous minor adjustments and further including means forquickly making a major adjustment between said fixed and rotatablemembers.

9. A Vmechanism of the character described comprising a shaft, 9. memberpositively connected to saidtshait, a plurality of members freelymounted on said shaft, means adjustably interconnecting said freelymounted members in predetermined angular relaticn,'and means connectingone of said freely mounted members to said positively connected member,the last named means including an angular adjustment that isoflsetlateraliynwith respect to said shaft.

HERBERT W. ALDEN. LAURENCE R. BUCKENDALE.

